Process for the preparation of surface treated mineral filler products and uses of same

ABSTRACT

The present invention relates to a process for preparing a surface treated mineral filler product, and to its preferred use in the field of plastic applications, and in particular polypropylene (PP)- or polyethylene (PE)-based breathable or extrusion coating film applications.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. application Ser. No. 13/697,567, filed Feb.7, 2013, which is a U.S. national phase of PCT Application No.PCT/EP2011/058409, filed May 24, 2011, which claims priority to EuropeanApplication No. 10164408.6, filed May 28, 2010 and U.S. ProvisionalApplication No. 61/396,938, filed Jun. 4, 2010, the contents of whichare hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a process for preparing a surfacetreated mineral filler product, and to its preferred use in the field ofplastic applications, and in particular polypropylene (PP)- orpolyethylene (PE)-based breathable or extrusion coating filmapplications.

Mineral fillers and especially calcium carbonate-containing mineralfillers are often used as particulate fillers in polymer productsusually made of polyethylene (PE), polypropylene (PP), polyurethane (PU)and polyvinylchloride (PVC). However, calcium carbonate-containingmineral fillers are generally associated with the presence of volatilesevolving at temperatures reached during the application of such mineralfillers and/or in the processing of polymer products comprising suchmineral fillers. Such volatiles may, for example, be:

-   -   inherently associated with the mineral filler (“inherent        volatiles”), and is especially associated water, and/or    -   introduced during the treatment of the mineral filler (“added        volatiles”), for example, to render the mineral filler more        dispersible within a polymeric plastic medium, and/or    -   generated by the reaction of inherent organic materials and/or        added organic materials, with the mineral filler; such reactions        may especially be induced or enhanced by temperatures reached        during the introduction and/or processing of the polymeric        material comprising the mineral filler, such as during the        extrusion or compounding process; and/or    -   generated by the degradation of inherent organic materials        and/or added organic materials, forming CO₂, water and possibly        low molecular mass fractions of these organic materials; such a        degradation may especially be induced or enhanced by        temperatures reached during the introduction and/or processing        of the polymeric material comprising the mineral filler, such as        during the extrusion or compounding process.

As a result of the presence of such volatiles, it may be difficult toprepare a polymer product free of voids leading to uneven surfaces andthus to a degradation of the quality of the final polymer productcomprising such mineral filler. This is particularly a problemencountered in the preparation of PP- or PE-based breathable orextrusion coating films comprising a mineral filler and moreparticularly calcium carbonate-containing mineral fillers. Moreover,volatiles may lead to a reduction in the tensile and tear strength ofsuch a film, and may degrade its visible aspects, in particular of itsvisible uniformity. Furthermore, volatiles can generate excessivefoaming of the mineral filled polymer melt during a step of compounding,causing unwanted product build-up at the vacuum extraction and hence,forcing a reduced output rate.

In the art, several attempts have been made to improve the applicabilityof mineral fillers and especially calcium carbonate-containing mineralfillers, e.g. by treating such mineral fillers with higher aliphaticcarboxylic acids, which in some cases may also be referred to as fattyacids, and aliphatic carboxylic acid salts. For instance, WO 00/20336relates to an ultrafine natural calcium carbonate, which may optionallybe treated with one or several fatty acids or one or several salts ormixtures thereof, and which is used as a rheology regulator for polymercompositions.

Likewise, U.S. Pat. No. 4,407,986 relates a precipitated calciumcarbonate that is surface-treated with a dispersant that may includehigher aliphatic acids and their metal salts in order to limit theaddition of lubricant additives when kneading this calcium carbonatewith crystalline polypropylene and to avoid the formation of calciumcarbonate aggregates that limit the impact strength of thepolypropylene.

In EP 0 325 114, relating to non-sagging underseal compositions formotor vehicles based on polyvinyl chloride which has improvedrheological and adhesion properties, Example 7 discloses a mixture of anammonium salt of 12-hydroxystearic acid in combination with a fatty acid(in a weight ratio of 1:1) used to treat a mineral filler.

WO 03/082966 relates to a cross-linkable and/or cross-linked nanofillercomposition which, in optional embodiments, may additionally includefillers that may or may not be coated with stearic acid, stearate,silane, siloxane and/or titanate. Such nanofiller compositions are usedto increase barrier properties, strength and heat distortiontemperatures, making them useful in medical, automotive, electrical,construction and food application.

US 2002/0102404 describes dispersible calcium carbonate particles coatedon their surface with a combination of saturated and unsaturatedaliphatic carboxylic acids and salts thereof along with an organiccompound such as a phthalic ester, which are used in adhesivecompositions to improve viscosity stability and adhesion properties.

Moreover, US 2002/0102404 requires the implementation of a mixture ofsaturated and unsaturated aliphatic carboxylic acids/salts. The presenceof unsaturated aliphatic carboxylic acids/salts increases the risk ofunwanted in situ side reactions with the double bond during processingof any unsaturated aliphatic carboxylic acid/salt-comprising material.Additionally, the presence of unsaturated aliphatic carboxylicacids/salts may result in discoloration of, or unwanted odourdevelopment, and notably rancid odours, in the material in which theyare implemented.

Claim 11 of WO 92/02587 indicates that a saponified sodium salt solutionof at least one high molecular weight unsaturated fatty acid orcombination of at least one high molecular weight unsaturated fatty acidand at least one high molecular weight unsaturated fatty acid, may beadded to a pre-heated slurry of precipitated calcium carbonate, toultimately produce a desired level of fatty acid coating on the calciumcarbonate before proceeding with further process steps.

The abstract of JP54162746 discloses a composition comprising givenrelative amounts of rigid vinyl chloride resin, fatty acidtreated-colloidal calcium carbonate, and barium stearate used in orderto improve the heat stability of the vinyl chloride composition.

U.S. Pat. No. 4,520,073 describes mineral filler materials with improvedhydrophobic coatings prepared by pressure coating of porous mineralsusing steam as a carrier for the coating material. Said coating materialmay be selected, among other options, from long chain aliphatic fattyacids and their salts.

WO 01/32787 describes a particulate alkaline earth metal carbonatematerial product which has on its particles a coating of hydrophobicmaterial comprising a composition formed of (a) a first component whichcomprises the reaction product of the alkaline earth metal carbonate andat least one given aliphatic carboxylic acid and (b) a second componenthaving a carbonate release temperature substantially higher than thefirst component comprises a compound of formula CH₃(CH₂)_(m)COOR.

However, the prior art does rarely disclose processes for preparingtreated mineral filler products which would solve the followingmultifaceted technical problems:

-   -   to prepare a treated mineral filler product by using a surface        treatment agent featuring a workable viscosity, that is to say a        Brookfield viscosity of less than 1000 mPa·s at 23° C.;    -   to prepare a treated mineral filler product having a high        volatile onset temperature above 220° C.    -   to prepare a treated mineral filler product such that it is        sufficiently hydrophobic for applications in plastics requiring        dispersability of said mineral filler in the polymer medium,        preferably such that said mineral filler is more hydrophobic        than if treated with carboxylic acids and/or carboxylic acid        salts having at least 10 carbon atoms treated at equal        temperature;    -   to prepare a treated mineral filler product having a low        moisture pick up susceptibility such that it is lower than that        of a mineral filler treated with carboxylic acids and/or        carboxylic acid salts having at least 10 carbon atoms treated at        equal temperature.    -   to identify a surface treatment agent for the process that        achieves the above regardless of whether or not the at least one        mineral filler undergoes a salt exchange on contact with the        surface treatment agent to create corresponding calcium salts on        the surface of the treated mineral filler.

In this regard, one obvious means to increase the volatile onsettemperature and to limit the corresponding quantity of total volatilesassociated with the mineral filler is to avoid or limit the use ofcertain common filler treatment additives. However, often, as in thecase when a mineral filler is applied in a plastic application, suchadditives are needed to ensure other functions.

For example, in the case of breathable film applications, additives areintroduced to provide the mineral filler with a hydrophobic coating andto improve the dispersability of the mineral filler in the filmprecursor material as well as possibly to improve the processability ofthis film precursor material and/or properties of the final applicationproducts. An elimination of such additives would unacceptably compromisethe resulting film quality.

In this regard, additional prior art, namely WO 99/61521 and WO2005/075353, which suggest a reduction of only the inherent water andpicked up humidity of the starting mineral filler, entirely missed thepoint of reducing the other volatiles besides water which contribute tothe total volatiles.

Thus, there is still a need for providing a process which addresses theforegoing technical problems described and especially allows forimproving the surface characteristics of a resulting treated mineralfiller product.

Accordingly, it is an objective of the present invention to provide aprocess for preparing a treated mineral filler product having improvedsurface characteristics, and especially a high volatile onsettemperature. A further objective is to provide a process for preparing atreated mineral filler product featuring a sufficient hydrophobicity forplastic applications. A still further objective is to provide a processfor preparing a treated mineral filler product featuring a low moisturepick up susceptibility. Another objective of the present invention is toprovide a process which can be carried out in a simple way. A furtherobjective is that the process can be carried out under cost-efficientand mild conditions, i.e. by avoiding an intensive thermal treatment.Further objectives can be gathered from the following description of theinvention.

The foregoing and other objectives are solved by the subject-matter asdefined herein in claim 1.

Advantageous embodiments of the inventive process are defined in thecorresponding sub-claims.

According to one aspect of the present application a process forpreparing a treated mineral filler product providing a volatile onsettemperature of at least 220° C. has been developed, wherein the processcomprises the steps of:

-   -   (a) providing at least one calcium carbonate-containing mineral        filler;    -   (b) providing at least one aliphatic aldehyde having between 6        and 14 carbon atoms;    -   (c) contacting said at least one mineral filler of step (a), in        one or more steps, with the at least one aliphatic aldehyde of        step (b) such that the added amount of said at least one        aliphatic aldehyde corresponds to a theoretical total weight of        between 0.25 mg/m² and 5 mg/m² on the surface of the treated        mineral filler product; and    -   (d) forming a treatment layer comprising said at least one        aliphatic aldehyde and/or reaction products of said at least one        aliphatic aldehyde on the surface of said at least one mineral        filler resulting in a treated mineral filler product.

The inventors surprisingly found that the foregoing process according tothe present invention avoids the use of intensive thermal treatments andleads to a treated mineral filler product providing a high volatileonset temperature of at least 220° C., a very good hydrophobicity andlow moisture pick up susceptibility. More precisely, the inventors foundthat the surface characteristics of a treated mineral filler productbeing obtained by said process can be improved by the addition ofdefined aliphatic aldehydes.

It should be understood that for the purposes of the present invention,the following terms have the following meanings:

The term “mineral filler” in the meaning of the present invention refersto substances of mineral origin added to materials such as paper,plastics, rubber, paints and adhesives, etc. to lower the consumption ofmore expensive materials such as binders, or to enhance technicalproperties of the products. The person skilled in the art very wellknows the typical fillers used in the respective fields.

The term “saturated” in the meaning of the present invention meanshaving an iodine number of less than 5 g I₂/100 g sample. This iodinenumber determination is well-known to the skilled man, and namelyimplements a determination of the iodine addition to a 100 g sample byback-titration of the surplus iodine with sodium thiosulfate.

The term “aliphatic aldehyde” in the meaning of the present inventionrefers to straight chain, branched chain, or alicyclic organic compoundscomposed of carbon and hydrogen.

Said organic compound further contains an aldehyde function, preferablyplaced at the end of the carbon skeleton.

The term “aliphatic carboxylic acid” in the meaning of the presentinvention refers to straight chain, branched chain, or alicyclic organiccompounds composed of carbon and hydrogen. Said organic compound furthercontains a carboxyl group placed at the end of the carbon skeleton.

The term “theoretical total weight” in the meaning of the presentinvention relates to the amount of treatment agent that would be presentin the treatment layer if all of said treatment agent is completelydeposited in the treatment layer.

The term “reaction products” in the meaning of the present inventionrefers to products typically obtained by contacting a mineral fillerwith a surface treatment agent. Said reaction products are preferablyformed between the applied surface treatment agent and molecule locatedat the surface of the mineral filler.

The term “volatile onset temperature” in the meaning of the presentapplication refers to a temperature at which volatiles—includingvolatiles introduced as a result of common mineral filler preparationsteps including grinding, with or without grinding aid agents,benefaction, with or without flotation aid or other agents, and otherpre-treatment agents not expressly listed above, detected according tothe thermogravimetric analysis described hereafter—begin to evolve, asobserved on a thermogravimetric (TGA) curve, plotting the mass ofremaining sample (y-axis) as a function of temperature (x-axis), thepreparation and interpretation of such a curve being defined hereafter.

TGA analytical methods provide information regarding losses of mass andvolatile onset temperatures with great accuracy, and is commonknowledge; it is, for example, described in “Principles of Instrumentalanalysis”, fifth edition, Skoog, Holler, Nieman, 1998 (first edition1992) in Chapter 31 pages 798 to 800, and in many other commonly knownreference works. In the present invention, thermogravimetric analysis(TGA) is performed using a Mettler Toledo TGA 851 based on a sample of500+/−50 mg and scanning temperatures from 25 to 350° C. at a rate of20° C./minute under an air flow of 70 ml/min.

The skilled man will be able to determine the “volatile onsettemperature” by analysis of the TGA curve as follows: the firstderivative of the TGA curve is obtained and the inflection pointsthereon between 150 and 350° C. are identified. Of the inflection pointshaving a tangential slope value of greater than 45° relative to ahorizontal line, the one having the lowest associated temperature above200° C. is identified. The temperature value associated with this lowesttemperature inflection point of the first derivative curve is the“volatile onset temperature”.

A “molten” or “liquid” state in the meaning of the present invention isdefined as the state in which a material is entirely liquid, in otherwords is entirely melted. Whereas the phenomenon of melting occurs atconstant temperature on application of energy, a substance is qualifiedas being molten as of the moment following melting when the temperaturebegins to rise, as observed on a curve plotting temperature versusenergy input obtained by Dynamic Scanning Calorimetry, DSC, (DIN 51005:1983-11).

The term “specific surface area” (in m²/g) of the mineral filler in themeaning of the present invention is determined using the BET method,which is well known to the skilled man (ISO 9277:1995). The totalsurface area (in m²) of the mineral filler is then obtained bymultiplication of the specific surface area and the mass (in g) of themineral filler prior to treatment.

The term “dry” mineral filler is understood to be a mineral fillerhaving less than 0.3% by weight of water relative to the mineral fillerweight. The % water is determined according to the Coulometric KarlFischer measurement method, wherein the mineral filler is heated to 220°C., and the water content released as vapour and isolated using a streamof nitrogen gas (at 100 ml/min) is determined in a Coulometric KarlFischer unit.

The term “molecules/m²” or “number of molecules/m²” in the meaning ofthe present invention is evaluated by determining the amount of therespective treatment agent (in mol) added for contacting the at leastone calcium carbonate-containing mineral filler and by calculating thetheoretical number of molecules of said amount by using the Avogadronumber [N_(A)] (6.02214179×10²³/mol).

The term “moisture pick up susceptibility” in the meaning of the presentinvention refers to the amount of moisture absorbed on the surface ofthe mineral filler and is determined in mg moisture/g of the dry treatedmineral filler product after exposure to an atmosphere of 50% ofrelative humidity for 48 hours at a temperature of 23° C.

The “hydrophobicity” of a mineral filler product is evaluated bydetermining the minimum methanol to water ratio in a methanol-watermixture needed for the settling of a majority of said mineral fillerproduct, where said mineral filler product is deposited on the surfaceof said methanol-water mixture by passage through a house hold teasieve.

As used herein and as generally defined in the art, the “d₅₀” value isdetermined based on measurements made by using a Sedigraph™ 5100 ofMicromeritics Instrument Corporation and is defined as the size at which50% (the median point) of the particle volume or mass is accounted forby particles having a diameter equal to the specified value. The methodand the instrument are known to the skilled person and are commonly usedto determine grain size of fillers and pigments. The measurement iscarried out in an aqueous solution of 0.1 wt.-% Na₄P₂O₇. The samples aredispersed using a high speed stirrer and supersonics.

The Brookfield viscosity as used herein and as generally defined in theart is measured by using a DV III Ultra model Brookfield viscometerequipped with the disc spindle 3 at a rotation speed of 100 rpm and roomtemperature (23±1° C.) after stirring for one minute.

According to another aspect of the present invention, a treated mineralfiller product is provided, wherein said mineral filler is obtainable bythe inventive process for preparing a treated mineral filler product.According to another aspect, the present invention refers to the use ofsaid treated mineral filler product in a process of mixing and/orextruding and/or compounding and/or blow moulding with plasticmaterials, in particular with plastic materials comprising polyolefinsor thermoplastics such as polyethylenes (PE), polypropylenes (PP),polyurethanes (PU) and/or polyvinylchlorides (PVC). According to anotheraspect, the present invention refers to films, and in particular filmsselected from the group comprising stretched and/or oriented films, andpreferably breathable films, or extrusion coating films, comprising thetreated mineral filler product.

According to one preferred embodiment of the inventive process, the atleast one calcium carbonate-containing mineral filler of step (a) isprecipitated calcium carbonate (PCC), namely one or more of thearagonitic, vateritic and calcitic mineralogical crystal forms, and/ornatural ground calcium carbonate (GCC), namely one or more of marble,limestone, or chalk, and/or dolomite and preferably is marble.

According to another preferred embodiment of the inventive process, theat least one aliphatic aldehyde of step (b) is selected from aliphaticaldehydes having 6 to 12 carbon atoms, preferably from aliphaticaldehydes having 6 to 9 carbon atoms and more preferably from aliphaticaldehydes having 8 or 9 carbon atoms.

According to yet another preferred embodiment of the inventive process,the at least one aliphatic aldehyde of step (b) is a saturated aliphaticaldehyde.

According to one preferred embodiment of the inventive process, the atleast one aliphatic aldehyde of step (b) features an equivalent isolatedviscosity of less than 500 mPa·s at 23° C. when measured in a DV IIIUltra model Brookfield viscometer equipped with the disc spindle 3 at arotation speed of 100 rpm and room temperature (23±1° C.).

According to another preferred embodiment of the inventive process, theat least one mineral filler provided in step (a) has a median particlesize diameter d₅₀ in the range between 0.3 μm and 10 μm, preferablybetween 0.5 μm and 5 μm, more preferably between 1 μm and 3 μm and mostpreferably between 1.5 μm and 1.8 μm and/or a specific surface area(BET) of between 1 m²/g and 10 m²/g and more preferably of between 3m²/g and 8 m²/g as measured by the BET nitrogen method.

According to yet another preferred embodiment of the inventive process,the at least one mineral filler of step (a) has a moisture content ofbetween 0.01 wt.-% and 1.0 wt.-%, preferably between 0.02 wt.-% and 0.9wt.-% and more preferably between 0.04 wt.-% and 0.2 wt.-%, based on thedry weight of the at least one mineral filler provided in step (a).

According to one preferred embodiment of the inventive process, step (c)further comprises contacting said at least one mineral filler of step(a) with at least one saturated aliphatic carboxylic acid having 6 to 28carbon atoms and/or at least one cation salt of one or more saturatedaliphatic carboxylic acids having 6 to 28 carbon atoms and preferablysaid saturated aliphatic carboxylic acid is selected from the groupconsisting of stearic acid, behenic acid, palmitic acid, isostearicacid, montanic acid, capric acid, lauric acid, myristic acid andmixtures thereof and more preferably being a 2:1 to 1:2 mixture (byweight) of stearic acid and palmitic acid.

According to another preferred embodiment of the inventive process, step(c) further comprises contacting said at least one mineral filler ofstep (a) with at least one polysiloxane, preferably selected frompolydimethylsiloxane.

According to yet another preferred embodiment of the inventive process,the treated mineral filler product obtained in step (d) features avolatile onset temperature of greater than or equal to 220° C., andpreferably of between 240° C. and 280° C.

According to one preferred embodiment of the inventive process, thetreated mineral filler product obtained in step (d) has a moisturecontent of between 0.01 wt.-% and 0.15 wt.-%, preferably between 0.02wt.-% and 0.12 wt.-% and more preferably between 0.04 wt.-% and 0.08wt.-% based on the dry weight of the at least one mineral filler of step(d).

According to another preferred embodiment of the inventive process, thetreated mineral filler product obtained in step (d) features a moisturepick up susceptibility such that its total surface moisture level isbelow 1.0 mg/g, more preferably below 0.5 mg/g and most preferably below0.4 mg/g of the dry treated mineral filler product after exposure to anatmosphere of 50% of relative humidity for 48 hours at a temperature of23° C.

As set out above, the inventive process for preparing a treated mineralfiller product having improved surface characteristics comprises thesteps of (a), (b), (c) and (d). In the following, it is referred tofurther details of the present invention and especially the foregoingsteps of the inventive process for preparing a treated mineral fillerproduct.

Characterization of Step (a): Provision of a CalciumCarbonate-Containing Mineral Filler

According to step (a) of the process of the present invention, at leastone calcium carbonate-containing mineral filler is provided.

A calcium carbonate-containing mineral filler in the meaning of thepresent invention refers to a calcium carbonate material selected fromground (or natural) calcium carbonate (GCC) or a precipitated, calciumcarbonate (PCC) or a mixture of GCC and PCC, optionally co-ground.

GCC is understood to be a naturally occurring form of calcium carbonate,mined from sedimentary rocks such as limestone or chalk, or frommetamorphic marble rocks and processed through a treatment such asgrinding, screening and/or fractionizing in wet and/or dry form, forexample by a cyclone or classifier. Preferably, the GCC is selected fromthe group comprising marble, chalk, dolomite, limestone and mixturesthereof.

By contrast, calcium carbonate of the PCC type include synthetic calciumcarbonate products obtained by carbonation of a slurry of calciumhydroxide, commonly referred to in the art as a slurry of lime or milkof lime when derived from finely divided calcium oxide particles inwater or by precipitation out of an ionic salt solution. PCC may berhombohedral and/or scalenohedral and/or aragonitic; preferred syntheticcalcium carbonate or precipitated calcium carbonate comprisingaragonitic, vateritic or calcitic mineralogical crystal forms ormixtures thereof.

In one preferred embodiment, the at least one calciumcarbonate-containing mineral filler is marble.

The at least one calcium carbonate-containing mineral filler of step (a)is preferably in the form of a particulate material, and may have aparticle size distribution as conventionally employed for thematerial(s) involved in the type of product to be produced. In general,the median particle size diameter d₅₀ value of the at least one calciumcarbonate containing-mineral filler is in the range between 0.3 μm and10 μm, preferably between 0.5 μm and 5 μm, more preferably between 1 mand 3 μm and most preferably between 1.5 μm and 1.8 μm. A mineral fillerd₉₈ of less than 25 microns, preferably of less than 10 microns may alsobe advantageous.

Additionally or alternatively, the at least one calciumcarbonate-containing mineral filler provided in step (a) exhibits a BETspecific surface area of from 1 m²/g to 10 m²/g and preferably ofbetween 3 m²/g and 8 m²/g measured using nitrogen and the BET methodaccording to ISO 9277.

In case the at least one calcium carbonate-containing mineral fillerprovided in step (a) in selected from GCC, the BET specific surface areais preferably of between 1 m²/g and 10 m²/g, more preferably of between3 m²/g and 8 m²/g and most preferably of between 3.5 m²/g and 4.5 m²/gas measured by the BET nitrogen method.

For example, if a marble is used as the at least one calciumcarbonate-containing mineral filler provided in step (a), the medianparticle size diameter d₅₀ value is preferably in the range between 1 μmand 3 μm, more preferably between 1.1 μm and 2.5 μm, even morepreferably between 1.2 μm and 2 μm and most preferably between 1.5 μmand 1.8 μm. In this case, the marble preferably exhibits a BET specificsurface area of from 3 m²/g to 6 m²/g, more preferably from 3.5 m²/g to5.5 m²/g and most preferably from 3.5 m²/g to 4.5 m²/g, measured usingnitrogen and the BET method according to ISO 9277.

By contrast, if a PCC is used as the at least one calciumcarbonate-containing mineral filler provided in step (a), the BETspecific surface area is preferably in the range of from 1 m²/g to 10m²/g, more preferably of from 3 m²/g to 8 m²/g, even more preferably offrom 6 m²/g to 7.5 m²/g and most preferably of from 6.5 m²/g to 7.5m²/g, measured using nitrogen and the BET method according to ISO 9277.

The at least one calcium carbonate-containing mineral filler provided instep (a) is a dry ground material, a material being wet ground and driedor a mixture of the foregoing materials. In general, the grinding stepcan be carried out with any conventional grinding device, for example,under conditions such that refinement predominantly results from impactswith a secondary body, i.e. in one or more of: a ball mill, a rod mill,a vibrating mill, a roll crusher, a centrifugal impact mill, a verticalbead mill an attrition mill, a pin mill, a hammer mill, a pulveriser, ashredder, a de-clumper, a knife cutter, or other such equipment known tothe skilled man.

In case a wet ground calcium carbonate-containing mineral filler isprovided in step (a), the grinding step may be performed underconditions such that autogenous grinding takes place and/or byhorizontal ball milling, and/or other such processes known to theskilled man. The wet processed ground calcium carbonate-containingmineral filler thus obtained may be washed and dewatered by well knownprocesses, e.g. by flocculation, filtration or forced evaporation priorto drying. The subsequent step of drying may be carried out in a singlestep such as spray drying, or in at least two steps, e.g. by applying afirst heating step to the mineral filler in order to reduce theassociated moisture content to a level which is not greater than about0.5 wt.-% based on the dry weight of the mineral filler, and applying asecond heating step to the calcium carbonate in order to reduce theremaining moisture content to a level which is about 0.15 wt.-% or less,based on the dry weight of the mineral filler. In case said drying iscarried out by more than one drying steps, the first step may be carriedout by heating in a hot current of air, while the second and furtherdrying steps are preferably carried out by an indirect heating in whichthe atmosphere in the corresponding vessel comprises a surface treatmentagent. It is also common that such a mineral filler undergoes abeneficiation step (such as a flotation, bleaching or magneticseparation step) to remove impurities.

In one preferred embodiment, the at least one calciumcarbonate-containing mineral filler provided in step (a) is a dry groundmineral filler. In another preferred embodiment, the at least onecalcium carbonate-containing mineral filler provided in step (a) is amaterial being wet ground in a horizontal ball mill, and subsequentlydried by using the well known process of spray drying. In still anotherpreferred embodiment, the at least one calcium carbonate-containingmineral filler provided in step (a) is a material produced by drygrinding followed by aqueous low solids wet grinding at 10 wt.-% to 30wt.-% solid material content, thermal or mechanical concentration to 40wt.-% to 60 wt.-% solid material content and subsequent drying.

The grinding of the at least one calcium carbonate-containing mineralfiller provided in step (a) is preferably carried out in absence of adispersing agent.

Depending on the at least one calcium carbonate-containing mineralfiller provided in step (a), the total surface moisture content ispreferably less than 1.0 wt.-% based on the dry weight of the calciumcarbonate-containing mineral filler provided in step (a), even afterexposure for 48 hours at 23° C. to a moisture atmosphere having arelative humidity of 50%.

In one preferred embodiment, the at least one calciumcarbonate-containing mineral filler provided in step (a) has a totalsurface moisture content of between 0.01 wt.-% and 1.0 wt.-%, preferablybetween 0.02 wt.-% and 0.9 wt.-% and more preferably between 0.04 wt.-%and 0.7 wt.-% based on the dry weight of the calciumcarbonate-containing mineral filler provided in step (a), even afterexposure for 48 hours at 23° C. to a moisture atmosphere having arelative humidity of 50%.

For example, in case a GCC is used as the at least one calciumcarbonate-containing mineral filler provided in step (a), the totalsurface moisture content is preferably of between 0.01 wt.-% and 1.0wt.-%, more preferably between 0.02 wt.-% and 0.15 wt.-% and mostpreferably between 0.04 wt.-% and 0.07 wt.-% based on the dry weight ofthe calcium carbonate-containing mineral filler provided in step (a),even after exposure for 48 hours at 23° C. to a moisture atmospherehaving a relative humidity of 50%. In this case, said GCC is for exampleselected from wet ground and spray dried marble. Preferably, the wetgrinding is done at low solids, e.g. at <35 wt % in absence ofdispersants.

If a PCC is used as the at least one calcium carbonate-containingmineral filler provided in step (a), the total surface moisture contentis preferably of between 0.01 wt.-% and 1.0 wt.-%, more preferablybetween 0.1 wt.-% and 0.9 wt.-% and most preferably between 0.4 wt.-%and 0.7 wt.-% based on the dry weight of the calciumcarbonate-containing mineral filler provided in step (a), even afterexposure for 48 hours at 23° C. to a moisture atmosphere having arelative humidity of 50%.

Step (b): Provision of at Least One Aliphatic Aldehyde

According to step (b) of the process of the present invention at leastone aliphatic aldehyde having between 6 and 14 carbon atoms is provided.

In this regard, the at least one aliphatic aldehyde represents a surfacetreatment agent and may be selected from any linear, branched oralicyclic, substituted or non-substituted, saturated or unsaturatedaliphatic aldehyde. Said aldehyde is preferably chosen such that thenumber of carbon atoms is greater than or equal to 6 and more preferablygreater than or equal to 8. Furthermore, said aldehyde has generally anumber of carbon atoms that is lower or equal to 14, preferably lower orequal to 12 and more preferably lower or equal to 10. In one preferredembodiment, the number of carbon atoms of the aliphatic aldehyde isbetween 6 and 14, preferably between 6 and 12 and more preferablybetween 6 and 10.

In another preferred embodiment, the at least one aliphatic aldehyde ispreferably chosen such that the number of carbon atoms is between 6 and12, more preferably between 6 and 9, and most preferably 8 or 9.

The aliphatic aldehyde may be selected from the group of aliphaticaldehydes consisting of hexanal, (E)-2-hexenal, (Z)-2-hexenal,(E)-3-hexenal, (Z)-3-hexenal, (E)-4-hexenal, (Z)-4-hexenal, 5-hexenal,heptanal, (E)-2-heptenal, (Z)-2-heptenal, (E)-3-heptenal,(Z)-3-heptenal, (E)-4-heptenal, (Z)-4-heptenal, (E)-5-heptenal,(Z)-5-heptenal, 6-heptenal, octanal, (E)-2-octenal, (Z)-2-octenal,(E)-3-octenal, (Z)-3-octenal, (E)-4-octenal, (Z)-4-octenal,(E)-5-octenal, (Z)-5-octenal, (E)-6-octenal, (Z)-6-octenal, 7-octenal,nonanal, (E)-2-nonenal, (Z)-2-nonenal, (E)-3-nonenal, (Z)-3-nonenal,(E)-4-nonenal, (Z)-4-nonenal, (E)-5-nonenal, (Z)-5-nonenal,(E)-6-nonenal, (Z)-6-nonenal, (E)-6-nonenal, (Z)-6-nonenal,(E)-7-nonenal, (Z)-7-nonenal, 8-nonenal, decanal, (E)-2-decenal,(Z)-2-decenal, (E)-3-decenal, (Z)-3-decenal, (E)-4-decenal,(Z)-4-decenal, (E)-5-decenal, (Z)-5-decenal, (E)-6-decenal,(Z)-6-decenal, (E)-7-decenal, (Z)-7-decenal, (E)-8-decenal,(Z)-8-decenal, 9-decenal, undecanal, (E)-2-undecenal, (Z)-2-undecenal,(E)-3-undecenal, (Z)-3-undecenal, (E)-4-undecenal, (Z)-4-undecenal,(E)-5-undecenal, (Z)-5-undecenal, (E)-6-undecenal, (Z)-6-undecenal,(E)-7-undecenal, (Z)-7-undecenal, (E)-8-undecenal, (Z)-8-undecenal,(E)-9-undecenal, (Z)-9-undecenal, 10-undecenal, dodecanal,(E)-2-dodecenal, (Z)-2-dodecenal, (E)-3-dodecenal, (Z)-3-dodecenal,(E)-4-dodecenal, (Z)-4-dodecenal, (E)-5-dodecenal, (Z)-5-dodecenal,(E)-6-dodecenal, (Z)-6-dodecenal, (E)-7-dodecenal, (Z)-7-dodecenal,(E)-8-dodecenal, (Z)-8-dodecenal, (E)-9-dodecenal, (Z)-9-dodecenal,(E)-10-dodecenal, (Z)-10-dodecenal, 1-dodecenal, tridecanal,(E)-2-tridecenal, (Z)-2-tridecenal, (E)-3-tridecenal, (Z)-3-tridecenal,(E)-4-tridecenal, (Z)-4-tridecenal, (E)-5-tridecenal, (Z)-5-tridecenal,(E)-6-tridecenal, (Z)-6-tridecenal, (E)-7-tridecenal, (Z)-7-tridecenal,(E)-8-tridecenal, (Z)-8-tridecenal, (E)-9-tridecenal, (Z)-9-tridecenal,(E)-10-tridecenal, (Z)-10-tridecenal, (E)-11-tridecenal,(Z)-11-tridecenal, 12-tridecenal, butadecanal, (E)-2-butadecenal,(Z)-2-butadecenal, (E)-3-butadecenal, (Z)-3-butadecenal,(E)-4-butadecenal, (Z)-4-butadecenal, (E)-5-butadecenal,(Z)-5-butadecenal, (E)-6-butadecenal, (Z)-6-butadecenal,(E)-7-butadecenal, (Z)-7-butadecenal, (E)-8-butadecenal,(Z)-8-butadecenal, (E)-9-butadecenal, (Z)-9-butadecenal,(E)-10-butadecenal, (Z)-10-butadecenal, (E)-11-butadecenal,(Z)-11-butadecenal, (E)-12-butadecenal, (Z)-12-butadecenal,13-butadecenal, and mixtures thereof. In a preferred embodiment, thealiphatic aldehyde is selected from the group consisting of hexanal,(E)-2-hexenal, (Z)-2-hexenal, (E)-3-hexenal, (Z)-3-hexenal,(E)-4-hexenal, (Z)-4-hexenal, 5-hexenal, heptanal, (E)-2-heptenal,(Z)-2-heptenal, (E)-3-heptenal, (Z)-3-heptenal, (E)-4-heptenal,(Z)-4-heptenal, (E)-5-heptenal, (Z)-5-heptenal, 6-heptenal, octanal,(E)-2-octenal, (Z)-2-octenal, (E)-3-octenal, (Z)-3-octenal,(E)-4-octenal, (Z)-4-octenal, (E)-5-octenal, (Z)-5-octenal,(E)-6-octenal, (Z)-6-octenal, 7-octenal, nonanal, (E)-2-nonenal,(Z)-2-nonenal, (E)-3-nonenal, (Z)-3-nonenal, (E)-4-nonenal,(Z)-4-nonenal, (E)-5-nonenal, (Z)-5-nonenal, (E)-6-nonenal,(Z)-6-nonenal, (E)-7-nonenal, (Z)-7-nonenal, 8-nonenal and mixturesthereof.

In another preferred embodiment, the at least one aliphatic aldehyde ofstep (b) is a saturated aliphatic aldehyde. In this case the aliphaticaldehyde is selected from the group consisting of hexanal, heptanal,octanal, nonanal, decanal, undecanal, dodecanal, tridecanal, butadecanaland mixtures thereof. Preferably, the at least one aliphatic aldehyde ofstep (b) in the form of a saturated aliphatic aldehyde is selected fromthe group consisting of hexanal, heptanal, octanal, nonanal, decanal,undecanal, dodecanal and mixtures thereof. For instance, the at leastone aliphatic aldehyde of step (b) in the form of a saturated aliphaticaldehyde is selected from octanal, nonanal and mixtures thereof.

If a mixture of two aliphatic aldehydes, e.g. two saturated aliphaticaldehydes such as octanal and nonanal is used according to the presentinvention, the weight ratio of octanal and nonanal is from 70:30 to30:70 and more preferably from 60:40 to 40:60. In one especiallypreferred embodiment of the present invention, the weight ratio ofoctanal and nonanal is about 1:1.

The at least one aliphatic aldehyde of the present invention ispreferably added such that the added amount of said at least onealiphatic aldehyde corresponds to a theoretical total weight of between0.25 mg/m² and 5 mg/m² on the surface of the treated mineral fillerproduct.

In one preferred embodiment, the at least one aliphatic aldehyde of thepresent invention is preferably added such that the amount of said atleast one aliphatic aldehyde corresponds to a theoretical total weightof less than 5 mg, more preferably less than 4.5 mg and most preferablyless than 4.0 mg/m² on the surface of the treated mineral filler productof the at least one calcium carbonate-containing mineral filler providedin step (a).

In another preferred embodiment, the at least one aliphatic aldehyde ofthe present invention is added in an amount of about 0.1 wt.-% to 1.5wt.-%, more preferably of about 0.1 wt.-% to 1.0 wt.-%, even morepreferably of about 0.2 wt.-% to 0.8 wt.-% and most preferably of about0.2 wt.-% to 0.6 wt.-%, based on the dry weight of the at least onecalcium carbonate-containing mineral filler provided in step (a).

In another aspect of the present invention, the process for preparing atreated mineral filler product providing a volatile onset temperature ofat least 220° C. comprises the steps of:

-   -   (a) providing at least one calcium carbonate-containing mineral        filler;    -   (b) providing at least one aliphatic aldehyde having between 6        and 14 carbon atoms;    -   (c) contacting said at least one mineral filler of step (a), in        one or more steps, with the at least one aliphatic aldehyde of        step (b) such that the added number of molecules of said at        least one aliphatic aldehyde corresponds to a theoretical total        number of molecules of from 1×10¹⁹/m² to 3×10¹⁹/m² on the        surface of the treated mineral filler product; and    -   (d) forming a treatment layer comprising said at least one        aliphatic aldehyde and/or reaction products of said at least one        aliphatic aldehyde on the surface of said at least one mineral        filler resulting in a treated mineral filler product.

In one preferred embodiment, the at least one aliphatic aldehyde ispreferably added such that the theoretical total number of molecules ofsaid at least one aliphatic aldehyde on the surface of the treatedmineral filler product is from 1×10⁹/m² to 2×10¹⁹/m² of the at least onecalcium carbonate-containing mineral filler provided in step (a).

Additionally or alternatively, it is to be noted that the at least onealiphatic aldehyde of step (b) of the inventive process is provided as aliquid at room temperature, i.e. said at least one aliphatic aldehydefeatures an equivalent isolated viscosity of less than 500 mPa·s at 23°C. when measured in a DV III Ultra model Brookfield viscometer equippedwith the disc spindle 3 at a rotation speed of 100 rpm and roomtemperature (23±1° C.).

Step (c): Contacting the Mineral Filler with Said at Least One AliphaticAldehyde

According to step (c) of the inventive process, the at least one calciumcarbonate-containing mineral filler of step (a) is contacted, in one ormore steps, with the at least one aliphatic aldehyde of step (b) suchthat the added amount of said at least one aliphatic aldehydecorresponds to a theoretical total weight of between 0.25 mg/m² and 5mg/m² on the surface of the treated mineral filler product.

Step (c) of contacting the at least one calcium carbonate-containingmineral filler with the at least one aliphatic aldehyde preferably takesplace under mixing conditions. The skilled man will adapt these mixingconditions (such as the configuration of mixing pallets and mixingspeed) according to his process equipment.

In one preferred embodiment, the inventive process may be a continuousprocess. In this case, it is possible to contact the at least onecalcium carbonate-containing mineral filler with the at least onealiphatic aldehyde in a constant flow, so that a constant concentrationof the aldehyde is provided during step (c). In another preferredembodiment, the inventive process may be a batch process, i.e. the atleast one calcium carbonate-containing mineral filler is contacted withthe at least one aliphatic aldehyde in more than one steps, wherein saidaliphatic aldehyde is preferably added in about equal portions.Alternatively, it is also possible to add the aliphatic aldehyde inunequal portions to the at least one calcium carbonate-containingmineral filler, i.e. in larger and smaller portions.

When implementing the at least one aliphatic aldehyde provided in step(c), it features a workable viscosity at about room temperature, i.e.the at least one aliphatic aldehyde is in a liquid state. Therefore, thecontacting of the at least one calcium carbonate-containing mineralfiller with the at least one aliphatic aldehyde may be carried out atlower treatment temperatures than that used in processes implementingcarboxylic acids and/or carboxylic acid salts having e.g. more than 10carbon atoms. In a preferred embodiment, the contacting of the at leastone calcium carbonate-containing mineral filler with the at least onealiphatic aldehyde is carried out at treatment temperatures of below120° C. and most preferably of below 110° C. In another preferredembodiment, the contacting of the at least one mineral filler with theat least one aliphatic aldehyde is carried out at temperatures ofbetween 15 and 150° C., more preferably of between 15 and 110° C., e.g.of about 80° C. or 100° C.

The treatment time for carrying out the contacting of the at least onecalcium carbonate-containing mineral filler with the at least onealiphatic aldehyde is carried out for a period of 30 min or less,preferably for a period of 20 min or less and more preferably for aperiod of 15 min or less. In general, the length of contacting the atleast one calcium carbonate-containing mineral filler with the at leastone aliphatic aldehyde is determined by the treatment temperatureapplied during step (c). For example, where a treatment temperature ofabout 100° C. is applied, the treatment time is as short as, forexample, about 5 or 10 minutes. If a treatment temperature of about 80°C. is applied, the treatment time can be as long as, for example, about10 or 15 minutes. In case the inventive process is implemented as acontinuous process, the treatment time is preferably less than 60 sec,more preferably less than 10 sec and most preferably less than 5 sec.

In a preferred embodiment, the contacting of step (c) may furthercomprise contacting said at least one calcium carbonate-containingmineral filler of step (a) with at least one saturated aliphaticcarboxylic acid having 6 to 28 carbon atoms and/or at least one cationsalt of one or more saturated aliphatic carboxylic acids having 6 to 28carbon atoms.

Such contacting of the at least one calcium carbonate-containing mineralfiller with at least one saturated aliphatic carboxylic acid and/or atleast one cation salt of one or more saturated aliphatic carboxylicacids may be carried out during and/or after the contacting of themineral filler with the at least one aliphatic aldehyde. If thecontacting of the at least one calcium carbonate-containing mineralfiller with at least one saturated aliphatic carboxylic acid and/or atleast one cation salt of one or more saturated aliphatic carboxylicacids is carried out simultaneously to the addition of the at least onealiphatic aldehyde of step (b), the contacting is preferably carried outat temperatures of between 60° C. and 150° C., for example, of between80° C. and 120° C. In this case, the length of the contacting of the atleast one calcium carbonate-containing mineral filler with the at leastone aliphatic aldehyde and the at least one saturated aliphaticcarboxylic acid and/or the at least one cation salt of one or moresaturated aliphatic carboxylic acids is determined by the treatmenttemperature applied during said contacting. For example, where atreatment temperature of about 100° C. is applied, the treatment time isas short as, for example, about 10 minutes.

In case, the contacting of the at least one calcium carbonate-containingmineral filler with the at least one saturated aliphatic carboxylic acidand/or at least one cation salt of one or more saturated aliphaticcarboxylic acids is carried out simultaneously to the addition of the atleast one aliphatic aldehyde of step (b), the at least one saturatedaliphatic carboxylic acid and/or at least one cation salt of one or moresaturated aliphatic carboxylic acids and the at least one aliphaticaldehyde are preferably provided in a blend of the at least onesaturated aliphatic carboxylic acid and/or the at least one cation saltof one or more saturated aliphatic carboxylic acids dissolved in the atleast one aliphatic aldehyde. Therefore, when implementing such blend,it features a workable viscosity at about room temperature, i.e. theblend is in a liquid state.

In a preferred embodiment, said at least one saturated aliphaticcarboxylic acid is chosen from aliphatic monocarboxylic acids.Alternatively or additionally, they may be linear aliphatic carboxylicacids and/or hydroxylated (i.e. OH group-comprising) aliphaticcarboxylic acids.

In this regard, the at least one saturated aliphatic carboxylic acid ispreferably chosen such that the number of carbon atoms is lower or equalto 28, preferably lower or equal to 24, more preferably lower or equalto 22, more preferably lower or equal to 20 and most preferably lower orequal to 18. Furthermore, said carboxylic acid has generally a number ofcarbon atoms that is greater than or equal to 6, preferably greater thanor equal to 10, more preferably greater than or equal to 12 and mostpreferably greater than or equal to 14. In one preferred embodiment, thenumber of carbon atoms of the at least one saturated aliphaticcarboxylic acid is between 6 and 28, preferably between 10 and 24, morepreferably between 12 and 22, even more preferably between 12 and 20 andmost preferably between 14 and 18.

For example, the at least one saturated aliphatic carboxylic acid isselected from the group consisting of stearic acid, behenic acid,palmitic acid, isostearic acid, montanic acid, capric acid, lauric acid,myristic acid and mixtures thereof. In one preferred embodiment, the atleast one saturated aliphatic carboxylic acid is selected from stearicacid and/or palmitic acid and/or myristic acid and/or lauric acid ormixtures thereof, and most preferably is stearic acid and/or palmiticacid.

If a mixture of two saturated aliphatic carboxylic acids, e.g. stearicacid and palmitic acid is used according to the present invention, theweight ratio of stearic acid and palmitic acid is from 3:1 to 1:3 andmore preferably from 2:1 to 1:2. In one especially preferred embodimentof the present invention, the weight ratio of stearic acid and palmiticacid is about 1:1.

In case, the contacting of step (c) comprises contacting said at leastone calcium carbonate-containing mineral filler of step (a) with atleast one cation salt of one or more saturated aliphatic carboxylicacids having 6 to 28 carbon atoms, the cation of the salt is preferablyselected from the second main group of the periodic system, such ascalcium, magnesium and/or strontium. For example, the cation of saidsalt is selected from calcium and/or magnesium.

Furthermore, it is preferred that the equivalent isolated mixture of theat least one saturated aliphatic carboxylic acid and/or at least onecation salt of one or more saturated aliphatic carboxylic acids featuresa viscosity of less than 10000, preferably of less than 1000, and morepreferably of less than 500 mPa·s at 180° C.

The at least one saturated aliphatic carboxylic acid and/or the at leastone cation salt of one or more saturated aliphatic carboxylic acids ofthe present invention are preferably added in a quantity such that theadded amount of said at least one saturated aliphatic carboxylic acidand/or the at least one cation salt of one or more saturated aliphaticcarboxylic acids and/or the at least one aliphatic aldehyde correspondsto a theoretical total weight of between 0.25 mg/m² to 5 mg/m² on thesurface of the treated mineral filler product.

In one preferred embodiment, the at least one aliphatic aldehyde of thepresent invention is preferably added in a quantity such that the addedamount of said at least one saturated aliphatic carboxylic acid and/orthe at least one cation salt of one or more saturated aliphaticcarboxylic acids and/or the at least one aliphatic aldehyde correspondsto a theoretical total weight of less than 5 mg, more preferably lessthan 4.5 mg and most preferably less than 4 mg/m² on the surface of thetreated mineral filler product.

In another preferred embodiment, the at least one saturated aliphaticcarboxylic acid and/or the at least one cation salt of one or moresaturated aliphatic carboxylic acids of the present invention is addedin an amount of about 0.1 wt.-% to 1.5 wt.-%, more preferably in therange of about 0.1 wt.-% to 1.0 wt.-%, even more preferably in the rangeof about 0.2 wt.-% to 0.8 wt.-% and most preferably in the range ofabout 0.2 wt.-% to 0.6 wt.-%, based on the dry weight of the at leastone calcium carbonate-containing mineral filler provided in step (a).

Additionally or alternatively, it is also possible that additionaltreatment agents that do not correspond to the at least one aliphaticaldehyde, nor to the at least one saturated aliphatic carboxylic acidand/or at least one cation salt of one or more saturated aliphaticcarboxylic acids are implemented in the process of the presentinvention. In such a case, it is preferred that this additionaltreatment agent is at least one polysiloxane, and more preferably apolydimethylsiloxane (PDMS).

The at least one polysiloxane is preferably added such that the amountof the at least one polysiloxane on the surface of the treated mineralfiller product corresponds to a theoretical total weight of less than0.1 mg/m², more preferably less than 0.075 mg/m² and most preferablyless than 0.05 mg/m².

In this regard, it is to be noted that such contacting of the at leastone calcium carbonate-containing mineral filler with the at least onepolysiloxane may be carried out during or after the contacting of the atleast one calcium carbonate-containing mineral filler with the at leastone aliphatic aldehyde. In one preferred embodiment, such contactingwith the at least one polysiloxane is carried out after the contactingof the at least one calcium carbonate-containing mineral filler with theat least one aliphatic aldehyde. In this case, the contacting ispreferably carried out at temperatures of between 90° C. and 110° C.,for example, of about 100° C. The length of contacting the at least onecalcium carbonate-containing mineral filler with the at least onepolysiloxane is determined by the treatment temperature applied duringsaid contacting. For example, where a treatment temperature of about100° C. is applied, the treatment time is as short as, for example,about 5 minutes.

In a preferred embodiment, the contacting of the at least one calciumcarbonate-containing mineral filler with the at least one polysiloxaneis carried out after the simultaneous addition of the at least onealiphatic aldehyde of step (b) and the at least one saturated aliphaticcarboxylic acid and/or at least one cation salt of one or more saturatedaliphatic carboxylic acids.

Step (d): Forming of a Treatment Layer

According to step (d) of the process of the present invention, atreatment layer comprising said at least one aliphatic aldehyde and/orreaction products of said at least one aliphatic aldehyde is formed onthe surface of said at least one calcium carbonate-containing mineralfiller resulting in a treated mineral filler product.

Step (d) of forming of the treatment layer comprising said at least onealiphatic aldehyde and/or reaction products of said at least onealiphatic aldehyde on the surface of said at least one calciumcarbonate-containing mineral filler preferably takes place under anatmosphere of air (23 vol.-% O₂/78 vol.-% N₂).

Furthermore, the treatment layer is characterized in that the addedamount of said at least one aliphatic aldehyde corresponds to atheoretical total weight of between 0.25 to 5 mg/m² on the surface ofthe treated mineral filler product.

In one preferred embodiment, the treatment layer is characterized inthat the added amount of said at least one aliphatic aldehydecorresponds to a theoretical total weight of less than 5 mg, morepreferably less than 4.5 mg and most preferably less than 4.0 mg/m² onthe surface of the treated mineral filler product.

It is further to be noted that the treatment layer of the treatedmineral filler product may comprise the at least one aliphatic aldehydeand/or further surface treatment agents such as the at least onesaturated aliphatic carboxylic acid and/or at least one cation salt ofone or more saturated aliphatic carboxylic acids in the form of reactionproducts obtained by contacting the mineral filler with the respectivesurface treatment agent.

The resulting treated mineral filler products obtained according to thepresent invention have improved surface characteristics in comparison tomineral fillers treated with carboxylic acids and/or carboxylic acidsalts having at least 10 carbon atoms, i.e. without the implementationof the at least one aliphatic aldehyde. The resulting treated mineralfiller products obtained from the inventive process provide a volatileonset temperature that is higher than that obtained for mineral fillerstreated with carboxylic acids and/or carboxylic acid salts having atleast 10 carbon atoms. Additionally, the treated mineral filler productsobtained from the inventive process provide a moisture pick upsusceptibility that is lower than that obtained for mineral fillerstreated with carboxylic acids and/or carboxylic acid salts having atleast 10 carbon atoms. Furthermore, the resulting treated mineral fillerproducts obtained from the inventive process provide a sufficienthydrophobicity for plastic applications. Said volatile onset temperatureand other surface characteristics relating to the present invention aredetermined in accordance with the measurement method defined above andshown in the example section here below.

In a preferred embodiment of the inventive process, the treated mineralfiller product obtained in step (d) features a volatile onsettemperature of greater than or equal to 220° C., and preferably ofbetween 230° C. and 300° C. Moreover, the obtained treated mineralfiller product has preferably a higher volatile onset temperature thanthe same mineral filler having a treatment layer but wherein the atleast one aliphatic aldehyde is replaced with carboxylic acids and/orcarboxylic acid salts having at least 10 carbon atoms.

Furthermore, the treated mineral filler products obtained from theinventive process provide a low moisture pick up susceptibility. It ispreferred that the moisture pick up susceptibility of the treatedmineral filler product obtained in step (d) is such that its totalsurface moisture level is below 1.0 mg/g, more preferably below 0.5 mg/gand most preferably below 0.4 mg/g of the dry treated mineral fillerproduct, after exposure to an atmosphere of 50% of relative humidity for48 hours at a temperature of 23° C. In another preferred embodiment, themoisture pick up susceptibility of the treated mineral filler productobtained in step (d) is such that its total surface moisture level isless than 0.35 mg/g, more preferably less than 0.3 mg/g and mostpreferably less than 0.25 mg/g of the dry treated mineral fillerproduct, after exposure to an atmosphere of 50% of relative humidity for48 hours at a temperature of 23° C. In still another preferredembodiment, the treated mineral filler product obtained in step (d) hasa moisture content of between 0.01 wt.-% and 0.15 wt.-%, preferablybetween 0.02 wt.-% and 0.12 wt.-% and more preferably between 0.04 wt.-%and 0.08 wt.-% based on the dry weight of the at least one mineralfiller of step (d).

The treated mineral filler product thus obtained may advantageously beimplemented in a process of mixing and/or extruding and/or compoundingand/or blow moulding with plastic materials, and preferably with PVC,polyolefins, such as polyethylene (PE), polypropylene (PP) and/orpolyurethanes (PU), particularly to obtain film materials, namelystretched/oriented film materials, and preferably breathable filmmaterials, or extrusion coating film materials.

In particular, film materials selected from the group comprisingstretched and/or oriented films, and preferably breathable films, orextrusion coating films are characterised in that they contain saidtreated mineral filler product obtainable by the process of the presentinvention.

In this regard, films according to the invention are characterized inthat they contain treated mineral filler products obtainable by theprocess of the present invention and in that they have less voidsleading to uneven surfaces and improved visible uniformity. As anotheradvantage, the mineral filler product obtained by the process of thepresent invention causes a higher output rate.

The following examples may additionally illustrate the invention but arenot meant to restrict the invention to the exemplified embodiments. Theexamples below show the high volatile onset temperature and the reducedmoisture pick up susceptibility of the treated mineral filler accordingto the present invention:

EXAMPLES

All measurement methods implemented in the examples are describedhereabove.

Example 1 Comparative Example

Example 1 refers to the treatment of a wet ground and spray dried marblewith a 1:1 mixture of stearic acid and palmitic acid at a treatmenttemperature of about 130° C. and the subsequent treatment withpolydimethylsiloxane.

500 g of a dry ground, followed by wet ground and spray dried marblefrom Carrara, Italy, wet ground at 25 wt.-% in tap water in a horizontalball mill (Dynomill 1.4 liter volume) and spray dried, featuring a d₅₀of approximately 1.6 microns, a specific surface area of 4.1 m²/g and ahumidity of 0.06 wt.-% was added to an MTI Mixer and the mixing wasactivated at 3000 rpm. Thereafter a 1:1 mixture (by weight) of drystearic acid powder and dry palmitic acid powder at room temperature wasintroduced to the mixer in a quantity so as to obtain the mg oftreatment agent per m² of marble indicated in Table 1, and the mixercontents were heated to 130° C. The contents of the mixer were mixed at130° C. under a stirring speed of 3000 rpm for a period of 10 minutes.Thereafter polydimethylsiloxane (Dow Corning 200 Fluid 1000 CS) wasintroduced to the mixer in a quantity so as to obtain the mg oftreatment agent per m² of marble indicated in Table 1. The contents ofthe mixer were mixed at 100° C. under a stirring speed of 3000 rpm for asecond period of 5 minutes.

The product thus obtained was thereafter analysed; the results arepresented in Table 1.

Example 2 Example of the Invention

Example 2 refers to the treatment of a wet ground and spray dried marblewith heptanal at a treatment temperature of about 80° C.

500 g of a wet ground and spray dried marble from Carrara, Italy, wetground at 25 wt.-% in tap water in a horizontal ball mill (Dynomill) andspray dried featuring a d₅₀ of approximately 1.6 microns, a specificsurface area of 4.1 m²/g and a humidity of 0.06 wt.-% was added to anMTI Mixer and the mixing was activated at 3000 rpm. Thereafter heptanal(Aldrich W254002) was introduced to the mixer in a quantity so as toobtain the mg of treatment agent per m² of marble indicated in Table 1,and the mixer contents were heated to 80° C. The contents of the mixerwere mixed at 80° C. under a stirring speed of 3000 rpm for a period of10 minutes.

The product thus obtained was thereafter analysed; the results arepresented in Table 1.

Example 3 Example of the Invention

Example 3 refers to the treatment of a wet ground and spray dried marblewith octanal at a treatment temperature of about 80° C.

500 g of a dry ground, followed by wet ground and spray dried marblefrom Carrara, Italy, wet ground at 25 wt.-% in tap water in a horizontalball mill (Dynomill) and spray dried featuring a d₅₀ of approximately1.6 microns, a specific surface area of 4.1 m²/g and a humidity of 0.05wt.-% was added to an MTI Mixer and the mixing was activated at 3000rpm. Thereafter octanal (Aldrich W279714) was introduced to the mixer ina quantity so as to obtain the mg of treatment agent per m² of marbleindicated in Table 1, and the mixer contents were heated to 80° C. Thecontents of the mixer were mixed at 80° C. under a stirring speed of3000 rpm for a period of 10 minutes.

The product thus obtained was thereafter analysed; the results arepresented in Table 1.

Example 4 Example of the Invention

Example 4 refers to the treatment of a wet ground and spray dried marblewith undecanal at a treatment temperature of about 80° C.

500 g of a dry ground, followed by wet ground and spray dried marblefrom Carrara, Italy, wet ground at 25 wt.-% in tap water in a horizontalball mill (Dynomill) and spray dried featuring a d₅₀ of approximately1.6 microns, a specific surface area of 4.1 m²/g and a humidity of 0.05wt.-% was added to an MTI Mixer and the mixing was activated at 3000rpm. Thereafter undecanal (Aldrich U2202) was introduced to the mixer ina quantity so as to obtain the mg of treatment agent per m² of marbleindicated in Table 1, and the mixer contents were heated to 80° C. Thecontents of the mixer were mixed at 80° C. under a stirring speed of3000 rpm for a period of 10 minutes.

The product thus obtained was thereafter analysed; the results arepresented in Table 1.

Example 5 Example of the Invention

Example 5 refers to the treatment of a wet ground and spray dried marblewith dodecanal at a treatment temperature of about 80° C.

500 g of a dry ground, followed by wet ground and spray dried marblefrom Carrara, Italy, wet ground at 25 wt.-% in tap water in horizontalball mill (Dynomill) and spray dried featuring a d₅₀ of approximately1.6 microns, a specific surface area of 4.1 m²/g and a humidity of 0.05wt.-% was added to an MTI Mixer and the mixing was activated at 3000rpm. Thereafter dodecanal (Aldrich D222003) was introduced to the mixerin a quantity so as to obtain the mg of treatment agent per m² of marbleindicated in Table 1, and the mixer contents were heated to 80° C. Thecontents of the mixer were mixed at 80° C. under a stirring speed of3000 rpm for a period of 5 minutes.

The product thus obtained was thereafter analysed; the results arepresented in Table 1.

TABLE 1 1 2 3 4 5 Test Comparative Invention Invention InventionInvention Mineral CaCO3 (GCC) CaCO3 (GCC) CaCO3 (GCC) CaCO3 (GCC) CaCO3(GCC) Treatment agents 1. carboxylic acid C16/C18 acids 2. aliphaticaldehyde heptanal octanal undercanal dodecanal 3. further additive 500ppm polydimethyl siloxane Total of treatment 1 and 2 2.4 mg/m² of 3.4mg/m² of 3.4 mg/m² of 3.7 mg/m² of 3.4 mg/m² of mineral mineral mineralmineral mineral Number of molecules of 5.3 × 10¹⁸/m² of 1.8 × 10¹⁹/m² of1.6 × 10¹⁹/m² of 1.3 × 10¹⁹/m² of 1.1 × 10¹⁹/m² of treatment agent 1 and2 mineral mineral mineral mineral mineral Treatnent Temp. (° C.) 130° C. 80° C.  80° C.  80° C.  80° C. Treatment Time (min.)  10/5  10  10  10 5 Moisture content in ppm 700 750 710 640 600 Treatment agent solidLiquid Liquid Liquid Liquid at 20° C. Not measurable <500 mPa · s <500mPa · s <500 mPa · s <500 mPa · s Brookfield visc. of carboxylicacid/aliphatic aldehyde Volatile onset temperature 244° C. 230° C. 233°C. 221° C. 244° C. Water pick up (mg/g)  0.33  0.27  0.21  0.32   0.2723° C., 50% rel .Humidity exposure time 48 hours Hydrophobic inH₂O/methanol  40/60  40/60  40/60  40/60  40/60 (v/v)

The invention claimed is:
 1. A treated mineral filler product obtainedby a process comprising the steps of: (a) providing at least one calciumcarbonate-containing mineral filler; (b) providing at least onealiphatic aldehyde having between 6 and 14 carbon atoms; (c) contactingthe at least one mineral filler of step (a), in one or more steps, withthe at least one aliphatic aldehyde of step (b) such that the addedamount of the at least one aliphatic aldehyde corresponds to atheoretical total weight of between 0.25 mg/m2 and 5 mg/m2 on thesurface of the treated mineral filler product; and (d) forming atreatment layer comprising the at least one aliphatic aldehyde and/orreaction products of the at least one aliphatic aldehyde on the surfaceof the at least one calcium carbonate-containing mineral filler of step(a) resulting in a treated mineral filler product having a volatileonset temperature of at least 220° C.
 2. The product according to claim1, wherein the at least one calcium carbonate-containing mineral fillerof step (a) is precipitated calcium carbonate (PCC) and/or naturalground calcium carbonate (GCC).
 3. The product according to claim 1,wherein the at least one calcium carbonate-containing mineral filler ofstep (a) is precipitated calcium carbonate (PCC) in one or more ofaragonitic, vateritic and calcitic mineralogical crystal forms.
 4. Theproduct according to claim 1, wherein the at least one calciumcarbonate-containing mineral filler of step (a) is natural groundcalcium carbonate (GCC) comprising ground marble, limestone, chalk,and/or dolomite.
 5. The product according to claim 1, wherein the atleast one aliphatic aldehyde of step (b) is an aliphatic aldehyde having6 to 12 carbon atoms.
 6. The product according to claim 1, wherein theat least one aliphatic aldehyde of step (b) is an aliphatic aldehydehaving 6 to 9 carbon atoms.
 7. The product according to claim 1, whereinthe at least one aliphatic aldehyde of step (b) is an aliphatic aldehydehaving 8 or 9 carbon atoms.
 8. The product according to claim 1, whereinthe at least one aliphatic aldehyde of step (b) is a saturated aliphaticaldehyde.
 9. The product according to claim 1, wherein the at least onealiphatic aldehyde of step (b) features an equivalent isolated viscosityof less than 500 mPa·s at 23° C.
 10. The product according to claim 1,wherein the at least one mineral filler provided in step (a) has amedian particle size diameter d₅₀ in the range between 0.3 μm and 10 μm.11. The product according to claim 1, wherein the at least one mineralfiller provided in step (a) has a specific surface area (BET) of between1 m²/g and 10 m²/g as measured by the BET nitrogen method.
 12. Theproduct according to claim 1, wherein the at least one mineral fillerprovided in step (a) has a specific surface area (BET) of between 3 m²/gand 8 m²/g as measured by the BET nitrogen method.
 13. The productaccording to claim 1, wherein the at least one mineral filler of step(a) has a moisture content of between 0.01 wt.-% and 1.0 wt.-%, based onthe dry weight of the at least one mineral filler provided in step (a).14. The product according to claim 1, wherein step (c) further comprisescontacting the at least one mineral filler of step (a) with at least onesaturated aliphatic carboxylic acid having 6 to 28 carbon atoms and/orat least one cation salt of one or more saturated aliphatic carboxylicacids having 6 to 28 carbon atoms.
 15. The product according to claim 1,wherein step (c) further comprises contacting the at least one mineralfiller of step (a) with a saturated aliphatic carboxylic acid selectedfrom the group consisting of stearic acid, behenic acid, palmitic acid,isostearic acid, montanic acid, capric acid, lauric acid, myristic acid,and any mixtures thereof.
 16. The product according to claim 1, whereinstep (c) further comprises contacting the at least one mineral filler ofstep (a) with a 2:1 to 1:2 mixture (by weight) of stearic acid andpalmitic acid.
 17. The product according to claim 1, wherein step (c)further comprises contacting the at least one mineral filler of step (a)with at least one polysiloxane.
 18. The product according to claim 1,wherein step (c) further comprises contacting the at least one mineralfiller of step (a) with polydimethylsiloxane.
 19. The product accordingto claim 1, wherein the treated mineral filler product obtained in step(d) has a volatile onset temperature of greater than or equal to 220° C.20. The product according to claim 1, wherein the treated mineral fillerproduct obtained in step (d) has a volatile onset temperature of between230° C. and 300° C.
 21. The product according to claim 1, wherein thetreated mineral filler product obtained in step (d) has a moisturecontent of between 0.01 wt.-% and 0.15 wt.-%, based on the dry weight ofthe at least one mineral filler of step (d).
 22. The product accordingto claim 1, wherein the treated mineral filler product obtained in step(d) has a moisture content of between 0.02 wt.-% and 0.12 wt.-%, basedon the dry weight of the at least one mineral filler of step (d). 23.The product according to claim 1, wherein the treated mineral fillerproduct obtained in step (d) has a moisture content of between 0.04wt.-% and 0.08 wt.-%, based on the dry weight of the at least onemineral filler of step (d).
 24. The product according to claim 1,wherein the treated mineral filler product obtained in step (d) featuresa moisture pick up susceptibility such that its total surface moisturelevel is below 1.0 mg/g, of the dry treated mineral filler product afterexposure to an atmosphere of 50% of relative humidity for 48 hours at atemperature of 23° C.
 25. The product according to claim 1, wherein thetreated mineral filler product obtained in step (d) features a moisturepick up susceptibility such that its total surface moisture level isbelow 0.5 mg/g, of the dry treated mineral filler product after exposureto an atmosphere of 50% of relative humidity for 48 hours at atemperature of 23° C.
 26. The product according to claim 1, wherein thetreated mineral filler product obtained in step (d) features a moisturepick up susceptibility such that its total surface moisture level isbelow 0.4 mg/g, of the dry treated mineral filler product after exposureto an atmosphere of 50% of relative humidity for 48 hours at atemperature of 23° C.
 27. The product according to claim 1, wherein theat least one aliphatic aldehyde having between 6 and 14 carbon atoms isheptanal.
 28. The product according to claim 1, wherein the at least onealiphatic aldehyde having between 6 and 14 carbon atoms is octanal. 29.The product according to claim 1, wherein the at least one aliphaticaldehyde having between 6 and 14 carbon atoms is undecanal.
 30. Theproduct according to claim 1, wherein the at least one aliphaticaldehyde having between 6 and 14 carbon atoms is dodecanal.